From patchwork Thu Mar 21 08:25:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Yang X-Patchwork-Id: 10863117 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 97D9E15AC for ; Thu, 21 Mar 2019 08:32:37 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7FD132A04A for ; Thu, 21 Mar 2019 08:32:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 744B02A05E; Thu, 21 Mar 2019 08:32:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 1EF1B2A04A for ; Thu, 21 Mar 2019 08:32:37 +0000 (UTC) Received: from localhost ([127.0.0.1]:33219 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h6t7s-000439-FO for patchwork-qemu-devel@patchwork.kernel.org; Thu, 21 Mar 2019 04:32:36 -0400 Received: from eggs.gnu.org ([209.51.188.92]:46639) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1h6t2F-0008Ot-EZ for qemu-devel@nongnu.org; Thu, 21 Mar 2019 04:26:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1h6t2D-00019k-DV for qemu-devel@nongnu.org; Thu, 21 Mar 2019 04:26:47 -0400 Received: from mga09.intel.com ([134.134.136.24]:44141) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1h6t29-00015V-IO for qemu-devel@nongnu.org; Thu, 21 Mar 2019 04:26:43 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 21 Mar 2019 01:26:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,252,1549958400"; d="scan'208";a="329280592" Received: from richard.sh.intel.com (HELO localhost) ([10.239.159.54]) by fmsmga006.fm.intel.com with ESMTP; 21 Mar 2019 01:26:39 -0700 From: Wei Yang To: qemu-devel@nongnu.org Date: Thu, 21 Mar 2019 16:25:55 +0800 Message-Id: <20190321082555.21118-7-richardw.yang@linux.intel.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190321082555.21118-1-richardw.yang@linux.intel.com> References: <20190321082555.21118-1-richardw.yang@linux.intel.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.24 Subject: [Qemu-devel] [PATCH 6/6] exec.c: add a check between constants to see whether we could skip X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, mst@redhat.com, Wei Yang , rth@twiddle.net Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP The maximum level is defined as P_L2_LEVELS and skip is defined with 6 bits, which means if P_L2_LEVELS < (1 << 6), skip never exceeds the boundary. Since this check is between two constants, which leverages compiler to optimize the code based on different configuration. Signed-off-by: Wei Yang --- exec.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/exec.c b/exec.c index 6c660f656c..5d71fdb89f 100644 --- a/exec.c +++ b/exec.c @@ -322,7 +322,8 @@ static void phys_page_compact(PhysPageEntry *lp, Node *nodes) assert(valid_ptr < P_L2_SIZE); /* Don't compress if it won't fit in the # of bits we have. */ - if (lp->skip + p[valid_ptr].skip >= (1 << 6)) { + if (P_L2_LEVELS >= (1 << 6) && + lp->skip + p[valid_ptr].skip >= (1 << 6)) { return; }